1. Field of the Invention
This invention relates to a master batch used in producing heat radiation shielding forms (extruded or molded forms) which are widely utilized for roofing and wall materials of buildings, window materials used at openings of automobiles, electric trains, aircrafts and so forth, arcades, ceiling domes, carports and so forth. More particularly, it relates to a master batch containing a heat radiation shielding component, used in producing transparent resin forms having good visible-light transmission properties and a superior heat radiation shielding performance, and also relates to a heat radiation shielding transparent resin form, and a heat radiation shielding transparent laminate, for which this master batch has been used.
2. Description of the Related Art
Solar radiations which enter various buildings and vehicles through their “openings” such as windows and doors include visible-light rays and besides ultraviolet radiations and infrared radiations. Among the infrared radiations included in such solar radiations, near-infrared radiations of 800 to 2,500 nm in wavelength are called heat radiations, and enter through the opening to cause a temperature rise in the room. In order to avoid such a temperature rise, in recent years, in the field of window materials for various buildings and vehicles, there is a rapid increase in demand for heat radiation shielding forms which can shield heat radiations while taking in visible-light rays sufficiently and can prevent the temperature rise in the room while keeping brightness. Patents concerning such heat radiation shielding forms are proposed in a large number.
For example, a heat radiation shielding sheet is proposed in which a heat radiation reflecting film comprising a transparent resin film on which a metal or a metal oxide has been vacuum-deposited is bonded to a transparent form such as a glass sheet, an acrylic sheet or a polycarbonate sheet (see Japanese Patent Applications Laid-open No. 61-277437, No. 10-146919, No. 2001-179887, etc.). However, this heat radiation reflecting film itself is very expensive and also requires a complicate process having a bonding step and so forth, resulting in a high cost. In addition, the heat radiation shielding sheet has a disadvantage that the adhesion between the transparent form and the reflecting film is not so good as to cause peeling of the film as a result of changes with time.
Heat radiation shielding sheets in which metals or metal oxides are directly vacuum-deposited on the surfaces of transparent forms are also proposed in a large number. These, however, have a problem that, in producing such heat radiation shielding sheets, an apparatus is necessary which requires environment control in a high vacuum and in a high precision, resulting in a bad mass productivity and poor general-purpose properties.
Besides, also proposed are, e.g., a heat radiation shielding sheet, and a film used therefor, in which an organic infrared absorber typified by a phthalocyanine compound or an anthraquinone compound is kneaded into a thermoplastic transparent resin such as polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyethylene resin or polystyrene resin (see Japanese Patent Applications Laid-open No. 6-256541, No. 6-264050, etc.). However, in order to shield the heat radiations sufficiently, the infrared absorber must be mixed in a large quantity. Its mixing in a large quantity leaves a problem that the ability to transmit visible light rays may lower. Also, since an organic compound is used, their use in window materials or the like for buildings and vehicles which are always directly exposed to sunlight involves a difficulty in weatherability, and can not necessarily said to be appropriate.
Further proposed is, e.g., a heat radiation shielding sheet in which inorganic particles of titanium oxide having heat radiation reflectivity or mica or the like coated with titanium oxide are kneaded into a transparent resin such as acrylic resin or polycarbonate resin (see Japanese Patent Applications Laid-open No. 2-173060, No. 5-78544, etc). This sheet, however, requires addition of heat radiation reflecting particles in a large quantity in order to improve heat radiation shielding power, so that the visible-light transmission properties may lower with an increase in the quantity of the heat radiation reflecting particles mixed. On the other hand, the addition of heat radiation reflecting particles in a small quantity may bring an improvement in the visible-light transmission power but may result in a low heat radiation shielding power. Thus, there has been a problem that it is difficult to satisfy the heat radiation shielding power and the visible-light transmission power simultaneously. In addition, the mixing of heat radiation reflecting particles in a large quantity involves a problem in view of strength that transparent resin forms may have low physical properties, in particular, a low impact resistance and a low toughness.
Under such technical backgrounds, the present inventors have already proposed a heat radiation shielding coating liquid in which fine hexaboride particles are incorporated in a binder of various types, and a heat radiation shielding film obtained by coating a form of various types with this coating liquid, followed by drying (see, e.g., Japanese Patent Applications Laid-open No. 11-181336, No. 2000-96034 and No. 2000-169765).
In these proposals, however, nothing has been brought forward with regard to master batches used in producing heat radiation shielding forms.